Title Description
Implement a trie with insert
, search
, and startsWith
methods.
Subject to the effect
Find realize the operation of the insert, search, and a prelude to a tree.
(Each tree node represents a lowercase letter, a complete word from the root to the leaf nodes represent)
Examples
E
Problem-solving ideas
Thanks thinking Leetcode @ cxq1992 provided, the method of engineering a more complete record keeping and operating tree node.
Complexity Analysis
Time complexity: O (NULL)
Space complexity: O (NULL)
Code
class node { public: node() : val(' '), end(false), shared(0) {} node(char c) : val(c), end(false), shared(0) {} node* subchild(char c) { if(!child.empty()) { for(auto chi : child) { if(chi->val == c) return chi; } } return NULL; } ~node() { for(auto chi : child) delete chi; } // The node tree stored lowercase char Val; // whether the node is a leaf node BOOL End; // number of child nodes int Shared; // child node stores Vector <Node *> Child; }; class Trie { public: /** Initialize your data structure here. */ Trie() { root = new node(); } /** Inserts a word into the trie. */ void insert(string word) { if(search(word)) return; node* cur = root; for(char c : word) { node* tmp = cur->subchild(c); if(tmp == NULL) { tmp = new node(c); cur->child.push_back(tmp); cur = tmp; } else { cur = tmp; } ++cur->shared; } cur->end = true; } /** Returns if the word is in the trie. */ bool search(string word) { node* tmp = root; for(char c : word) { tmp = tmp->subchild(c); if(tmp == NULL) return false; } return tmp->end; } /** Returns if there is any word in the trie that starts with the given prefix. */ bool startsWith(string prefix) { node* tmp = root; for(char c : prefix) { tmp = tmp->subchild(c); if(tmp == NULL) return false; } return true; } private: node* root; }; /** * Your Trie object will be instantiated and called as such: * Trie* obj = new Trie(); * obj->insert(word); * bool param_2 = obj->search(word); * bool param_3 = obj->startsWith(prefix); */